@article{MZ_1991__207_2_174290,
     author = {Heinrich Freist\"uhler},
     title = {Linear degeneracy and shock waves.},
     journal = {Mathematische Zeitschrift},
     pages = {583--596},
     publisher = {mathdoc},
     volume = {207},
     number = {2},
     year = {1991},
     zbl = {0756.35048},
     url = {http://geodesic.mathdoc.fr/item/MZ_1991__207_2_174290/}
}